The invention relates generally to medical devices for retrieving material from within a body. More particularly, the invention relates to medical retrieval baskets that have atraumatic distal ends that are contoured or tipless both to minimize the chances of damage to tissue during use and to enhance the ability of the basket to capture material (e.g., stones) disposed or lodged in xe2x80x9cpocketsxe2x80x9d or other areas that are difficult to access in the body.
Known stone retrieval devices typically have baskets that are constructed by joining multiple legs together at a base of the basket and at a distal end or tip of the basket such that a xe2x80x9ccagexe2x80x9d is formed. At the distal tip, the individual legs are joined by soldering, adhesives, etc. such that a protruding tip results. This protrusion or outward projection at the distal end of the basket can poke tissue and cause tissue trauma. In general, the tips or ends of known baskets protrude outward and thus can cause damage by poking or piercing tissue. Also, the protruding tips of known baskets generally do not permit access to or intimate contact with certain areas within the body such as xe2x80x9cpockets,xe2x80x9d and thus stones residing in such areas are difficult or impossible to retrieve with known baskets.
It is an object of the invention to provide a medical retrieval basket that does not have a substantially protruding distal basket end or basket tip. That is, a basket according to the invention is atraumatic and does not have any significant distal protrusion or outward projection that can poke tissue, pierce tissue, or otherwise cause trauma to tissue.
It is another object of the invention to provide a medical retrieval basket that permits access to and/or intimate contact with certain areas within the body such as xe2x80x9cpocketsxe2x80x9d where material to be retrieved (e.g., stones) might reside or be lodged, impacted, or embedded. A tipless or contoured tip basket arrangement can access these areas and retrieve material from those areas whereas a conventional basket with a traumatic tip would not be able to do so because of the traumatic protruding tip that prevents intimate contact between the distal end of the basket and body tissue.
It is yet another object of the invention to provide a method of using such baskets to retrieve material from within a body. The material can be biological or foreign matter. The material can be, for example, urological stones or any of a variety of other types of material found in the body.
A basket according to one aspect of the invention is tipless and thus lacks a protruding end or tip. At least a distal end portion of the basket can be formed from a single piece of material to achieve the desired tipless feature. The one-piece construction of at least the distal end portion of the tipless basket can be achieved by removing the desired profile from a flat sheet of construction material or by using an injection mold process. With this type of single unit, one-piece construction, the basket legs require joining only at the base of the basket where the basket is attached to a cable, coil, wire, etc., that connects the basket to a proximal handle mechanism. This single unit feature of baskets according to the invention can be achieved in a variety of ways including stamping, photoetching, laser cutting, and injection molding. Also, various materials can be used to form the tipless one-piece unit or the entire basket such as metal, polymers, ceramics, powdered metals, thermal plastic composites, etc. Combinations of these or other materials also may be used to manufacture a basket according to the invention.
The invention generally relates to a medical retrieval device that comprises a sheath, a handle, and an atraumatic basket. The sheath has a proximal end and a distal end. The handle is located at the proximal end of the sheath. The basket can remove material from a body, and it has a collapsed position where the basket is enclosed within the sheath and an expanded position where the basket extends from the distal end of the sheath. The basket can have three or more legs (e.g., four, five, or six legs). At least a distal end portion of the basket is substantially tipless and defined by a shape or profile which comprises a single continuous unit. In another embodiment of the invention, the atraumatic basket is formed by a plurality of wires, each wire forming a loop with a small protrusion at the very distal end of the basket.
In accordance with one aspect of the invention, the atraumatic basket has a distal end portion defined by a single continuous, one-piece unit. The atraumatic basket can include the following features. The distal end portion of the atraumatic basket can be non-perforated or perforated to, for example, allow a guidewire or lithotripsy device (laser) to extend through the sheath and through the end of the basket. The shape of the distal end portion of the atraumatic basket can be formed from, for example, metal, metal alloys, a ceramic material, a powdered metal, or a polymer. The basket legs, each of which has an inner surface and an outer surface, can have at least a portion of their inner surfaces coated with an anti-slip material, textured, or roughened in some manner to enhance the ability of the basket to grip and hold material. The atraumatic basket can be made by one-piece construction forming, as a single continuous one-piece unit, a shape having three or more legs, for example, a y-shape, x-shape, t-shape or star-shape, and then bending the legs of the shape to form at least a distal portion of a three-dimensional basket structure that is useful for retrieving objects. Other shapes such as a double loop may be used to form the distal portion of the basket. Shapes other than the ones described here also may be used to form the distal portion of the basket. The shape can be stamped, etched, and/or cut from a continuous sheet of material. Alternatively, the shape could be achieved by injection molding.
In another embodiment of an atraumatic wire basket, the distal ends of the basket wires insert into an inverted cap at the distal basket tip.
Another aspect of the invention relates to a method for manufacturing a basket for a medical retrieval device comprising the steps of forming, as a single continuous unit, a shape having three or more legs and bending the legs of the shape to form at least a portion of a three-dimensional basket structure for retrieving objects. The shape can be stamped, etched or cut from a continuous sheet of material. The shape can also be injection molded.
Yet another aspect of the invention features a method for retrieving material from a body including the steps of inserting an extractor into a body, the extractor including a basket having three or more legs and wherein at least a distal end portion of the basket is defined by a shape which comprises a single continuous unit, capturing the material within the basket and withdrawing the extractor from the body to remove the material from the body.
The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description and from the claims.